CITROEN DS3 Handbook page 192

Misfuel prevention (Diesel)*
Mechanical device which prevents filling the tank of a Diesel vehicle with petrol. It avoids the risk of engine damage that can result from filling with the
wrong fuel.
Located in the filler neck, the misfuel prevention device appears when the filler cap is removed.
Operation
When a petrol filler nozzle is introduced into the
fuel filler neck of your Diesel vehicle, it comes
into contact with the flap. The system remains
closed and prevents filling.
do not persist but introduce a diesel type
filler nozzle.
It remains possible to use a fuel can to
fill the tank.
In order to ensure a good flow of fuel,
do not place the nozzle of the fuel can
in direct contact with the flap of the
misfuel prevention device and pour
slowly.
Travelling abroad
As Diesel fuel pump nozzles may
be different in other countries, the
presence of the misfuel prevention
device may make refuelling impossible.
Before travelling abroad, we
recommend that you check with the
CITROËN dealer network, whether
your vehicle is suitable for the fuel
pumps in the country in which you want
to travel.
* According to country of sale.